The present invention relates to the care of infants, specifically the feeding of infants. More specifically, the invention relates to a nurser with a fluid containing bag therein and a one-way valve which allows fluid to be expelled from the bottle through a nipple while allowing air to enter a space between the bag and the outside shell of the nurser.
Nursing bottles, which may otherwise be referred to as baby bottles or nursers, are widely used in the care of infants. Specifically, nursing bottles have long been used to feed liquids to infants. Nursing bottles provide a convenient vehicle to contain liquids to be used in feeding without the fear of spillage. Further, nursing bottles provide a nipple on which the infant may use her instinctive sucking desire to consume the liquid.
Standard bottles equipped with nipples allowed the infant to suck on the nipple to withdraw liquid therefrom. However, this basic bottle has drawbacks. First, the removal of liquid from the bottle creates negative pressure within the bottle, making further removal of liquid more difficult. Second, air would come to the top of the liquid containing volume of the bottle. The infant frequently consumes this air, inducing unpleasant burping, coughing or other reactions. Rigid bottles cannot be squeezed to force air out of the liquid holding volume. Third, air enters the bottle to equalize pressure, after liquid is removed. This may result in contact with the feeding liquid by contaminants.
Improving upon the standard nursing bottle, bottles have been made from flexible material, such that a user could squeeze unwanted air out of the nipple end of the bottle before presenting an infant with the bottle for feeding therefrom. The bottle typically will return to its normal shape once pressure on the shell of the bottle is removed, allowing unwanted air to reenter the bottle during feeding.
Improving further upon the standard nursing bottle, bottles have been made as hollow tubes with removable end caps. This feature allowed the user to more easily and thoroughly clean the bottle.
Collapsible bags have been provided within the interior volume of the bottle to house the liquid. Openings were placed within the walls of the bottle to allow air to enter the expanding space between the bottle shell and the collapsing bag as liquid was withdrawn therefrom. This design reduced the chance of contaminants contacting the feeding liquid, by preventing the build up of negative pressure within the liquid holding volume.
Attempts have been made to provide for a valve in the bottle. This design is desirable because it allows air to enter the bottle as liquid is withdrawn therefrom (thereby preventing the build up of negative pressure), while allowing a user to squeeze the shell of the bottle to eject unwanted air out of the nipple and liquid holding volume before presenting the bottle to the infant for feeding.
Jamell U.S. Pat. No. 3,200,980 discloses a nursing bottle with a one-way valve comprising a ball confined within a channel of variable width. The ball moves vertically within the channel responsive to pressure differences between the outside of the bottle and the inside liquid holding volume. When the ball is lifted upwardly by a pressure gradient or the bottle is inverted, air is able to pass around the ball and enter the volume within the bottle.
Chen U.S. Pat. No. 4,685,577 discloses a nursing bottle comprising an air penetrating board with one-way air-inlet apertures thereon. The air apertures are constructed of a rubber like material disposed in an upwardly angled position such that a decrease in the interior liquid holding volume in relation to the outside pressure causes the apertures to open, allowing air to pass through the barrier into the liquid holding volume.
Vinciguerra U.S. Pat. No. 5,431,290 discloses a nursing bottle with a large, single one-way valve which operates in a similar fashion as the apertures disclosed in Chen. Rodriguez U.S. Pat. No. 5,699,921 discloses a similar system for allowing air to enter the interior of a nursing bottle through a one-way valve.
Lunden U.S. Pat. No. 2,907,485 discloses a rigid bottle with a flexible reusable liner positioned therein. A check valve mounted on the bottom of the bottle includes a first flexible disk having a centrally located opening. Mounted on the first flexible disk is a second relatively thin and flexible disk, having on its outer portion a plurality of circular openings. As fluid in the reusable liner is discharged through the nipple, the second disk is raised out of contact with the first flexible disk, permitting air to flow through the centrally located opening, between the two disks, through the plurality of circular openings and into the lower portion of the bottle. The air flows into the bottle until pressure equalization allows the second disk to relax, contacting the first disk, trapping the air therein.
Greenwood U.S. Pat. No. 5,499,729 discloses a rigid bottle having a removably mounted diaphragm member with a dome-shaped central portion. The dome-shaped portion is provided with a plurality of circular apertures or slits that are sealed shut when the diaphragm is in a relaxed state. The dome-shaped portion of the diaphragm member distends axially into the bottle interior in response to a pressure differential created during liquid consumption. In the distended state, the apertures in the diaphragm open to permit air to flow into the bottle until pressure equalization is achieved.
The present invention is directed to a nursing bottle with a one-way valve made from a resiliently flexible material in combination with a corresponding end cap. The disk is responsive to pressure changes inside the bottle relative to ambient air pressure.
The bottle comprises a vertically extending cylindrical shell, which is preferably made of a resiliently flexible plastic which will regain its original shape after being squeezed. The shell defines a hollow volume therein. The upper and lower ends of the shell are preferably threaded, capable of receiving end caps. The top end cap engages the threads of the upper end and secures a nipple therebetween. A collapsible bag is preferably held in place at its open upper edge by the top end cap and upper end of the shell. Liquid for feeding an infant is to be disposed within the bag. The top end cap and top of the shell, with the nipple and edge of the bag therebetween, form a seal for the bag.
A valve is located at the bottom of the bottle where the bottom end cap engages the lower end of the shell. The bottom end cap has at least one hole, preferably disposed in a central portion. A flexible disk rests upon the inside surface of the end cap. The disk is resiliently flexible and preferably made from silicone. The outer rim of the disk is engaged between the bottom end cap and the bottom surface of the shell, thereby forming a seal for the volume within the shell. Slits, preferably located in a radially positioned ring are provided in the disk.
When the nursing bottle is exposed to ambient air pressure only, the pressure within the bottle is equal to ambient and the disk rests on the base of the bottom end cap. Separate seals prevent air flow through the valve structure. First, the slits penetrating the flexible disk are closed. Second, a seal exists between the bottom of the slits in the disc and the base of the bottom end cap. Third, a seal exists between the holes in the bottom end and the disk. Fourth, the bag and/or nipple at the top of the shell seal the interior volume at the opposite end of the shell.
When a child care giver squeezes the shell of the bottle to eject air therefrom, the shell is compressed, causing the volume between the shell and the bag to become pressurized. The increased pressure pushes down upon the flexible disk, thereby further sealing the bottom end cap. The slits in the disk remain closed. Having no other means of pressure equalization, the increased pressure within the shell squeezes the collapsible bag, thereby forcing fluid out of the bag through the nipple. Once the care giver releases her squeeze on the bottle, the shell resiliently expands to its normal shape. The volume expansion causes a drop in pressure or a partial vacuum within the bottle. In the presence of the vacuum, ambient outside pressure acts on the flexible disk through holes in the bottom end cap. The disk bows slightly upward into the bottle, thereby opening the slits as the flexible material expands upwardly. With the seal open, air rushes into the volume between the shell and the collapsed bag, thereby equalizing the pressure. Air generally will not reenter the collapsed bag through the nipple because the valve provides a path of lesser resistance than does the aperture of the nipple.